Self-centering coil cradle



Oct. 27, 1964 H. F. FISCHER, JR., ETAL 3, 5 6

SELF-CENTERING con. CRADLE 2 Sheets-Sheet 1 Filed May 8, 1963 INVENTORS.HARRY Ff FISCHER. JQ. BLYAWRE/VCE 4.//09D,Jfi.

ATTORNEYS.

Oct. 27, 1964 H. F. FISCHER, JR.. ETAL 3,154,263}

SELF-CENTERING COIL CRADLE Filed May 8, 1963 2 Sheets-Sheet 2 INVENTORS.

"22 HARRY F2 FISCHER JR.

26 EL v ATTORNEKS BYLAWAENCE A. HOOQJR.

United States Patent Office 3,154,253 Patented Oct. 27, 1964 3,154,263SElZF-CEN 66E CRADLE F. Fischer, 313, and Lawrence A. Hood, .lr.,Pittsburgh, Pa, assign-01's to Zedco (30., inc., Ettshurgh, Ta, acorporation of Pennsylvania Filed May 8, 1953, Ser. No. 278,971 9Claims. (Cl. 24-278.7}

This invention relates to roller cradles for supporting coils of stripmaterial while they are being wound or unwound, and more particularly tocradles designed to keep the coils centered thereon.

in coiling or uncoiling a length of strip material it is common practiceto place or form the coil on a pair of parallel horizontal rollers sothat it can rotate. As the coil rotates, it generally will movelengthwise along the rollers slowly toward one end or the other, sostops or guides usually are provided to restrain the endwise movement ofthe coil. However, such guides are objectionable because they are apt todamage the edges of the strip engaging them. One solution to the problemhas been to make one of the cradle rollers in a special form that tendsto keep the coil from moving endwise in either direction from a centeredposition, but such a roller is relatively complicated and expensive.

it is among the objects of this invention to provide a coil cradle whichwill automatically keep a coil centered thereon, which does not requireend guides, which uses conventional rollers and which is simple andinexpensive in construction.

In accordance with this invention, one of a pair of laterally spacedsubstantially horizontal rollers is journaled at its ends in a pair ofbearings mounted in fixed position. The other roller, which is spacedfrom the first one just far enough to permit a coil of strip material torest on both rollers, also has its ends journaled in a pair of bearings,but these hearings are mounted on a supporting member which is rockablysupported in such a manner that it will be tilted lengthwise by a coilrotating on the rollers and starting to move lengthwise thereof from acentral position. The tilting roller is rotated directly or by the coilin such direction that its top turns toward the other roller so that thetilted coil will reverse its direction of axial movement and return tocentered position on the rollers.

The invention is illustrated in the accompanying drawings, in which PK}.1 is a plan view of our coil cradle;

FIG. 2 is a side view thereof with a coil resting on the cradle;

FIG. 3 is an end view of the cradle ant. coil; and

FlGS. 4, 5 and 6 are views, similar to FIGS. 1, 2 and 3, of amodification of the invention.

Referring to FIGS. 1 to 3 of the drawings, a pair of substantiallyparallel horizontal rollers 1 and 2 are disposed above a suitable base3. The ends of roller 1 are journaled in bearings 4, which are rigidlymounted on a support 5 fastened to the base. Preferably, this roller isdriven in any suitable manner, such as by a chain and sprocket drive 6mounted on an extension of the roller neck.

It is a feature of this invention that the other rol er 2 is mounted fortilting or roclc'ng movement in a vertical plane extending lengthwise ofthe roller. Accordingly, the ends or the roller are journaled inbearings 8 rigidly porting member 9, such as a thick plate, which isspaced mounted on the opposite ends of an elongated rigid suplaterallyfrom the support 5 beneath the other I The plate is supported above thebase by means disposed midway between the ends of the plate and whichrockaoly support it on a transverse axis. For best results, this axisshould be as high as possible. In the drawings the rockable support isformed in part by lugs ill projecting outward from the upper ends ofbrackets 11 extending upward from the opposite sides of the plate. Asshown in FIG. 2, each lug is tapered downward to form a knife edge thatrests in a V notch 12 in the top of a bearing block 13 rigidly mountedon the base beside the plate. The taper of the notches is flatter thanthat of the lugs so that the latter can rock in the notches to permitplate 9 and roller 2 to tilt lengthwise.

To normally hold the tilting roller level when there is no coil on thecradle, a vertical coil spring 14 may be compressed between each end ofplate 9 and the underlying base. These springs may be held in place bypins 15 projecting up into them from the base, but the upper ends of thepins are spaced from the overlying plate far enough to allow it to tiltsufiiciently for its intended purpose. On the other hand, the pins alsofunction as stops to prevent the plate from rocking too far in eitherdirection, such as when a coil is being placed on the cradle or removedfrom it.

Assuming that a coil C of strip material, such as metal strip, has beenplaced on the cradle in centered position so that the tilting roller 2is horizontal, the strip is unwound from the coil in a direction thatwill cause the top of roller 1 to turn away from the other roller.Either roller, or both can be driven, but it is easiest to drive roller1 because it has stationary bearings 4. As the coil obviously rotateswhile it is being unwound, it will almost certainly attempt to moveaxially along the rollers. However, because or" the construction of thecradle any such movement of the coil will start to tilt roller 2 and thecoil itself, whereupon the coil will reverse its axial movement and movetoward the higher end of the tilted roller and back to centeredposition. It may pass that position, but.

if it does, the tilting roller and coil will tilt in the oppositedirection so that the coil again will return toward centered position onthe cradle. Although the reason why the tilted coil travels toward thehigh end of the tilted roller is not fully understood, it apparently isbecause engagement between the tilted coil and the horizontal rohertends to change from a horizontal line contact to a point contact thatdescribes a helical path around the coil as it rotates that progressestoward the lower end of the coil. Since the horizontal roller cannotmove axially, this screwing of the tilted coil against the horizontalroller must move the coil axially along both rollers away from the lowerend of the tilted roller.

The weight of the coil will tend to push roller-supporting plate 9 awayfrom support 5, so to prevent the plate from binding against outerbearing block 13 various means can be used, such as a thrust bearing, orrollers engaging the outer side or" the plate. A simple way of solvingthe problem is to connect the inner side of plate 9 to support 5 by apair of flexible or pivoted tension links 16. To provide for lateralmovement of the plate toward the support when the plate tilts, theremust be some clearance between the plate and the two bearing blocks 33.

This cradle becomes more sensitive to axial movements of a coil on it asthe weight of the coil on the tilting roller increases relative to itsweight on the other roller. There.

fore, it is desirable to locate roller 1 at a higher elevation than theother roller in order to cause the coil to put more weight on thetilting roller, as shown in FIG. 3.

it will be seen that in actual practice there can be very little tiltingof the one roller because the moment the coil begins to tilt it, thecoil will start to move back in the opposite direction. Consequently, inpractice the tilting roller merely rocks back and forth as the coilstarts to move axially first in one direction and then in the other,with the result that the coil stays substantially centered on thecradle. However, as long as the pivot point for the tilting coil isbelow the coils center of gravity, there will be some overshooting ofcenter as the coil moves back and forth along the rollers. This isbecause a tilted coil will have to climb past the center point beforethe tilting roller will level out and then the roller will quickly tiltin the opposite direction. This problem is solved to some extent bysprings 14, which reduce the degree of roller tilting, but overshootingcan be practically eliminated by the embodiment of the invention shownin FIGS. 4 to 6.

In the modification shown in FIGS. 4, 5 and 6, one roller 21 isjournaled in permanent horizontal position in bearings 22 on a support23 as before, but the supporting member or plate 24 for the other roller25, instead of being carried by central pivot bearings, is mounted ontwo sets of wheels 26 or the like near its opposite ends. These wheels,in turn, travel on longitudinally concave track means 27 mounted on thebase 28. The track means have longitudinally concave upper surfaceslying in an arc of a circle, the axis of which coincides as closely aspossible with the center of the full coil supported by the rollers.Therefore, when the rotating coil starts to move axially from centeredposition on the rollers toward one end or the other, one end ofsupporting plate 24 will be pressed down and that will cause the wheelsto roll toward the opposite end of the tracks, thereby tilting the plateand roller 25 and the coil around the axis of the track are. The resultof this tilting will be the same as that described earlier; the coilwill move axially toward the higher end of the roller and thereforereturn to centered position on the rollers, which will level the tiltingroller. In doing this the coil will not have to pass centered position,because when the center of the coil reaches that position it willcoincide with the axis of the track arc. This arrangement therefore ismore sensitive than the one first described.

An important feature of this embodiment of the invention is that thecoil cradle can be made to compensate automatically for changes in theweight of the coil. This is done by making the track means 27 from apair of laterally spaced spring steel plates, so that the greater theweight on them the more they will be flattened. The initial curvature ofthe tracks is such that when a full coil is placed on the rollers thetracks will be flattened to the point where the axis of the track arewill pass approximately through the center of the coil. As the coil isunwound and it therefore becomes lighter, the tracks will be permittedto gradually bow upward to shorten their radius of curvature, wherebythe axis of the track arc and the center of the coil will remain closetogether.

According to the provisions of the patent statutes, we have explainedthe principle of our invention and have illustrated and described whatwe now consider to represent its best embodiment. However, we desire tohave it understood that, Within the scope of the appended claims, theinvention may be practiced otherwise than as specifically illustratedand described.

We claim:

1. A self-centering cradle for a coil of strip material, comprising apair of laterally spaced substantially horizontal rollers, a pair ofbearings for the ends of each roller, stationary supporting means forone pair of bearings, a supporting member for the other pair ofbearings, and means rockably supporting said member for lengthwisetilting by a coil rotating on said rollers and starting to movelengthwise thereof from a central position, the tilting roller beingrotatable in such direction that its top turns toward the other rollerso that a tilted coil will travel axially toward the high end of thetilted roller.

2. A cradle according to claim 1, in which the top of the horizontaltilting roller is at a lower level than the top of the other roller.

3. A cradle according to claim 1, including means for driving one ofsaid rollers in such direction that the bottom of the coil will travelfrom the tilting roll to the other roller.

4. A self-centering cradle for a coil of strip material, comprising apair of laterally spaced substantially horizontal rollers, a pair ofbearings for the ends of each roller, stationary supporting means forone pair of bearings, a supporting member for the other pair ofbearings, and means rockably supporting said member on a transverse axismidway between the ends thereof, whereby said memher will be tiltedlengthwise by a coil rotating on said rollers and starting to movelengthwise thereof from a central position, the tilting roller beingrotatable in such direction that its top turns toward the other rollerso that a tilted coil will travel axially toward the high end of thetilted roller.

5. A cradle according to claim 4, including springs beneath saidsupporting member tending to hold it horizontal.

6. A self-centering cradle for a coil of strip material, comprising abase, a pair of aligned bearings mounted thereon, a roller journaled insaid bearings, an elongated rigid supporting member spaced laterallyfrom said roller, means on said base midway between the ends of saidmember rockably supporting it above the base on a transverse axis sothat it can tilt lengthwise, a pair of aligned bearings mounted on theends of said member, a roller journaled in said last-mentioned bearings,whereby a rotating coil supported by the rollers will tilt the rollersupported by said rockable member if the coil starts to move axiallyfrom a central position, and means for driving said first-mentionedroller in such direction that its top turns away from the other roller.

7. A self-centering cradle for a coil of strip material, comprising apair of laterally spaced substantially horizontal rollers, a pair ofbearings for the ends of each roller, stationary supporting means forone pair of bearings, a supporting member for the other pair ofbearings, Wheels supporting said member for longitudinal movement, andlongitudinally concave track means for said wheels, whereby the wheelswill run along the track means and tilt said member when a coil rotatingon said rollers starts to move lengthwise of the rollers from a centralposition, the tilting roller being rotatable in such direction that itstop turns toward the other roller so that a tilted coil will travelaxially toward the high end of the tilted roller.

8. A coil cradle according to claim 7, in which said track means isbowed lengthwise and resilient and changes its curvature in accordancewith the weight supported by it;

9. A coil cradle according to claim 7, in which said track meansincludes two laterally spaced bowed spring plates.

References Cited in the file of this patent UNITED STATES PATENTS2,122,674 Wardle July 5, 1938 ha e...

1. A SELF-CENTERING CRADLE FOR A COIL OF STRIP MATERIAL, COMPRISING APAIR OF LATERALLY SPACED SUBSTANTIALLY HORIZONTAL ROLLERS, A PAIR OFBEARINGS FOR THE ENDS OF EACH ROLLER, STATIONARY SUPPORTING MEANS FORONE PAIR OF BEARINGS, A SUPPORTING MEMBER FOR THE OTHER PAIR OFBEARINGS, AND MEANS ROCKABLY SUPPORTING SAID MEMBER FOR LENGTHWISETILTING BY A COIL ROTATING ON SAID ROLLERS AND STARTING TO MOVELENGTHWISE THEREOF FROM A CENTRAL POSITION, THE TILTING ROLLER BEINGROTATABLE IN SUCH DIRECTION THAT ITS TOP TURNS TOWARD THE OTHER ROLLERSO THAT A TILTED COIL WILL TRAVEL AXIALLY TOWARD THE HIGH END OF THETILTED ROLLER.